In order to determine guide lines of penetration instruments in objects, it is often the case that an imaging method is firstly used to image the object which is intended to be penetrated by the penetration instrument and, if possible, determine prominent points within the object. For example, within the scope of so-called CT intervention, a computed tomography system can be used to make visible a tumor inside an organ of a patient, which tumor is intended to be ablated or extracted with the aid of an endoscopic instrument, or from which tissue samples are intended to be taken within the scope of a tumor biopsy. In the process, the location of tissue structures which should not be injured by the instrument, for example sensitive, healthy organs, is also made visible by the image data generated by the computed tomography system.
Such targeted penetration of a penetration instrument entering an object may also be necessary in very different applications, not all of which are in the field of medical technology. Firstly, the imaging method carries out non-invasive imaging, which makes it possible to identify a particular target object and provide the user of the penetration instrument with coordinates by way of which the instrument can be inserted into the object in a targeted manner so it can reach the respective location with the smallest amount of risk.
However, simple availability of the coordinates from the imaging method does not yet guarantee that a user can carry out such a penetration in a precise and targeted manner. Rather, to this end, it is necessary to mark out a guide line for the penetration instrument. Preferably, this occurs with the aid of automated marking out methods. To this end, DE 10 2005 030285 B4 proposes to use a marking out device which fixedly irradiates an intervention position with the aid of a laser beam. DE 198 01 446 A1 also discloses such a laser marking out, with the laser light source used for this purpose being displaceable along a rail.
Furthermore, U.S. Pat. No. 5,782,842 discloses marking out a guide line with the aid of two differently colored light beams, in particular using fan light beams. This guide line is defined by an entry point and an entry angle. However, it is often the case that the initial entry point and entry angle cannot be maintained during the insertion of the instrument, for example because the instrument would encounter, at a particular location within the object, regions which it cannot touch or which prevent it from further progress. In this respect, U.S. Pat. No. 5,782,842, using the light beam marking out, only represents a first starting point, from where and at what angle a user should firstly apply the instrument.